Reversing mechanism for double-action hydraulic oil well pump

ABSTRACT

A valve system for controlling input and exhaust of power fluid to a dual action hydraulically actuated downhole pump utilizes a ported inner mandrel slidably mounted over the middle rod of the pump and actuated by the pump pistons, with a ported valve housing located annularly between the mandrel and the production tubing.

United States Patent [191 Pugh [ Nov. 25, 1975 REVERSING MECHANISM FORDOUBLE-ACTION HYDRAULIC 01L WELL PUMP [75] Inventor:

[73] Assignee: Dresser Industries, Inc., Dallas, Tex.

[22] Filed: Apr. 15, 1974 [21] Appl. No.2 460,858

Toby Sydney Pugh, Arlington, Tex.

[52] U.S. Cl. 417/393; 91/324; 91/352;

. 91/413 [51] Int. Cl. F04B 17/00; F1513 13/09 ['58] Field of Search417/393, 394, 395, 401,

[56] References Cited UNITED STATES PATENTS 2/1966 Russell 417/3933,652,187 3/1972 Loeffler 417/393 3,846,048 11/1974 Robbins, Jr .14l7/393 3,849,030 11/1974 McArthur et al 417/393 Primary ExaminerC. J.Husar Assistant ExaminerLeonard Smith Attorney, Agent, or Firm-MichaelJ. Caddell [5 7] ABSTRACT A valve system for controlling input andexhaust of power fluid to a dual action hydraulically actuated downholepump utilizes a ported inner mandrel slidably mounted over the middlerod of the pump and actuated by the pump pistons, with a ported valvehousing located annularly between the mandrel and the production tubing.

5 Claims, 3 Drawing Figures US. Patent N0v.25, 1975 Sheet1of2 3,922,116

I 'a 1 4A US. Patent Nov. 25, 1975 FIG. 2A

REVERSING MECHANISM FOR DOUBLE-ACTION HYDRAULIC OIL WELL PUMP BACKGROUNDOF THE INVENTION In the production of oil from low pressure formations,it is often necessary when the well is not capable of flowing by itselfto utilize oil well pumps lowered into the production tubing in thewell. There are various and numerous types of production pumps one ofwhich is the mechanical or sucker rod type. This pump is driven byvertical reciprocation of a sucker rod string inside the tubing. Acommon sucker rod pump may be capable of pumping 200-300 barrels per dayfrom an average well.

An improved type of pump is the single action hydraulic pump whichutilizes hydraulic power supplied to the subsurface pump by a powerfluid which is pumped to the subsurface pump from equipment above groundat or near the wellhead. Such a pump on the average well may increaseproduction to as much as 1,500 barrels per day.

A further improvement involves the use of the doubleaction hydraulicpump which is capable of increasing the production capacity of thepumped well to as much as 2,500 barrels of oil per day.

The use of a double-action hydrualic pump requires a complex andefficient valving system for good performance, dependability, and longwear in the borehole. The valving system must be capable of supplyingpower fluid to one piston while allowing the power fluid on the oppositepiston to be expelled while also simultaneously one piston is pushingwell fluid up the production string and the opposite piston is drawingfluid up from the formation by means of a suction stroke.

The present invention provides a dual reversing valve system whichmaximizes the efficiency of the doubleaction hydraulic pump by providingoptimum timing and power fluid cycles through its porting system whilealso contributing to longer life, dependability and ease of manufacturebecause of its lack of unnecessary complexity. Furthermore, the presentinvention allows the use of maximum width pump pistons per given tubingsize thereby further optimizing pumping efficiency. The prior artsuffers in this respect in that a large portion of the effective pistonsurface area is used up by the passage of the valving mechanismtherethrough. The deficiency is eliminated by this invention.

BRIEF DESCRlPTlON OF THE DRAWINGS FIG. 1 is a schematic view of adouble-action hydraulic oil well pump;

FlGS. 2a and 2b illustrate a one-half section view of the valving systemof this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematiccross-sectional view of a dual action hydraulic oil well pumpingassembly located in a production tubing string 1 which is concentricallylocated in a producing wellbore 11.

The pumping assembly 10 consists generally of an upper piston assembly 2and a lower piston assembly 3 connected to the upper piston assembly bymiddle rod 4. The reversing valve assembly 5 is located around rod 4between the upper and lower piston assemblies. The piston assemblies andvalving mechanism are slidably 2 and sealingly located in a pump barrel6 secured inside the well tubing 1.

Pistons 2 and 3 in conjunction with pump barrel 6 form upper and lowerchambers 7 and 8 respectively and a power fluid chamber 9 between thepistons.

A producing formation 12 is penetrated by the wellbore 11 and flows oilunder low pressure into the wellbore below the pumping mechanism 10. Awell fluid pickup conduit 13 extends from the formation 12 to the 0upper and lower chambers 7 and 8. A pumped fluid conduit 14 extends fromchambers 7 and 8 to the surface to conduit pumped well fluid from thewell. A power fluid conduit 15 extends from hydraulic power supplyequipment at the surface to the power fluid chamber 9 via valvingassembly 5. Annular packings 24 and 25 provide sealing between the valveassembly 5 and the tubing 1.

Referring now to FIGS. 20 and 2b, a more detailed description of thevalvin g assembly 5 will be given. The figures represent a one-halfcross sectional view divided at the longitudinal centerline of thevalving assembly and broken at common line a-a.

The valving assembly utilizes a tubular ported inner mandrel 16 slidablyencircling middle rod 4. Mandrel 16 has an upper skirt 17 forming anannular space 17a between skirt l7 and the middle rod 4. A flow port 18extends through skirt 17 at its upper end and one or more elongatedslots 19 pass through the skirt below port 18. The lower end of mandrel16 is identical to the upper end but in an inverted orientation, makingmandrel 16 symmetrical about a lateral axis. The lower end of themandrel also has a skirt 20, annular space 20a, port 21 and slots 22.

An annular bumper ring 23 encircles mandrel l6 and is held thereon byengagement in a matching annular channel formed in the outer wall ofmandrel 16.

A vertically symmetrical valve housing assembly 26 is snugly mountedabout the inner mandrel and adapted to allow slidable movement of themandrel therein. The housing assembly 26 is generally cylindrical inshape and consists of an upper ported head 27, an upper ported connector28, a central cylinder 29, a lower ported connector 30, and a lowerported head 31.

The upper and lower heads are each secured to sections of the pumpbarrel 6a and 6b, respectively. The heads each have a set of one or moreports 32 and 33, respectively, passing therethrough.

The upper connector 28 is threadedly attached to upper head 27 andcontains an annular shoulder 33 thereon which, in conjunction with thelower end 34 of upper head 27, serves to secure the annular packing 24therebetween. Connector 28 has one or more ports 35 therethro'ugh whichcommunicate with an annular relief area 36 formed in the connectorinwardly from shoulder 33. Ports 35 are located so as to be able tocommunicate with ports 18 in the inner mandrel, while relief area 36 isadapted to communicate with slots 19 and also ports 18 during part ofstroke of mandrel 16.

The central cylinder 29 is a cylindrical sleeve thread edly secured toupper connector 28 and slidably enclosing annular bumper ring 23. Thelower connector 30 which is identical to upper connector 28 in aninverted orientation thereto, is threadedly secured to the centralcylinder and has ports 37 and relief area 38 arranged to communicatewith ports 21 and slots 22, re-

- spectively.

3 packing 25 similar to the attachment of packing 24 to the valveassembly. The lower head is threadedly secured to pump barrel 6b andcontains one or more ports 39 therethrough located so as to communicateat times with ports 21 or slots 22.

While not illustrated in FIGS. and 2b, it is noted that pistons 2 and 3are secured to middle rod 4 and serve to form with pump barrel sections6a and 6b upper and lower power fluid chambers 90 and 9b, respectively,below the upper piston and above the lower piston. Annular packings 24and serve as pressure seals between the tubing ID and the upper andlower connectors, respectively. Also the lower end of upper connector 28in conjunction with the upper end of lower connector provide theabutment means to receive bumper 23 and limit vertical movement ofmandrel 16.

Referring again to FIG. 1, in typical operation, the double-actionhydraulic pump 10 is actuated by supplying, under high pressure, powerfluid down conduit 15, which conduit is pictured inside the tubing butwhich could be outside the tubing. The fluid is supplied to thereversing valve assembly which directs it to either the bottom face ofthe upper piston 2 or the upper face of the lower piston 3.Simultaneously while delivering the power fluid to one piston face, itexhausts through a check valve spent power fluid from the opposite faceof the other piston. Also simultaneously, one piston chamber iscommunicated with the well fluid supply conduit 13 and the oppositepiston chamber is communicated with the pumped fluid discharge conduit14, which is shown inside the tubing but which could be outside thetubing or could actually be the tubing-casing annulus. Suitable checkvalves may be located in each of the conduits l3, l4 and 15 to preventbackflow.

The piston receiving power fluid application moves into its pistonchamber thereby forcing out pumped well fluid while the opposite pistonmoves out of its piston chamber setting up a suction and drawing in wellfluid from the formation. Upon reaching the piston stroke limit, thereversing valve switches power fluid from the pumping piston to thesuction piston and the pump then performs the second half of thedoubleaction pumping cycle.

At any point between the piston stroke limits, the pump assembly issimultaneously receiving power fluid, discharging spent power fluid,pumping well fluid to the surface, and drawing well fluid up to the pumpfrom the formation.

The use of the valving system of this invention makes the aboveoperation highly efficient and dependable. In operation, the valvingassembly as shown in FIGS. 2a and 2b, is in position to receive powerfluid through an inlet 41 in the tubing and apply the pressurized fluidthrough ports 35 and 18, and annular space 170 to power chamber 90 wherethe power fluid starts to force the upper piston upward. This serves topush out well fluid located in the piston chamber 7 above piston 2 whileit simultaneously brings the lower piston upward forcing out spent powerfluid in chamber 9b atop piston 3 while creating a suction in chamber 8below piston 3 and thereby drawing in well fluid to chamber 8.

Upon reaching a certain position in the upward stroke, the lower piston3 will abut the lower skirt 20 of mandrel 16 and begin to carry itupward inside the housing assembly 26. A rapid upward movement andconsequent possible damage to the valving assembly is prevented by therestricted damping action of the narrow annular passage 42 between theinner mandrel and upper connector 28. This passage provides fluidicresistance to flow of fluid trapped on top of bumper ring 23 and therebyacts as a dashpot effect to resist upward movement of the mandrel andpiston assembly upward in the housing assembly.

Likewise, a corresponding annular restricted passage 43 below bumper 23prevents an identical rapid movement downward on the downstroke portionof the pumping cycle.

As the piston and rod assembly and inner mandrel near the upper limit ofthe upstroke, ports 39 and 35 cease to communicate with slots 22 andports 18 and the moving inertia of the piston and rod assembly carriesthe assembly and the inner mandrel on upward until bumper ring 23 abutsthe lower end of connector 28. At this instant port 32 is placed incommunication with slot 19 and port 37 communicates with port 21 therebyputting pressurized power fluid onto the top of lower piston 3 andsimultaneously opening to exhaust the spent power fluid below the upperpiston 2 so that as piston 3 is forced downward the power fluid trappedbelow piston 2 may be discharged into the annulus through a check valve40.

The downward movement of the piston and rod assembly also serves to pumpwell fluid upward to the surface and draw well fluid up from the wellformation as previously described.

Upon reaching the lower limit of the pump downstroke, the upper piston 2will abut the upper end of mandrel 16 thereby driving it downward untilit is once again in the position as shown in FIGS. 2a and 2b whereuponthe pumping cycle is completed and another cycle is ready to begin.

It should be noted that near the end of each upstroke and eachdownstroke, all of the ports are closed for a split second to preventunwanted intercommunication between them and stalling of the pumpingoperation. The moving inertia of the piston and rod assembly and theinner mandrel is sufficient in each case to move the ports past thisintentionally included dead spot and into the next pump strokeoperation, thereby preventing short circuiting of the fluid flowchannels. Packing 24 and 25 further prevent fluid communication betweenthe upper ports and between the lower ports.

Although a specific preferred embodiment of the present invention hasbeen described in the detailed description above, the description is notintended to limit the invention to the particular forms of embodimentsdisclosed therein, since they are to be recognized as illustrativerather than restrictive and it will be obvious to those skilled in theart that the invention is not so limited. Thus, the invention isdeclared to cover all changes and modifications of the specific exampleof the invention herein disclosed for purposes of illustration which donot constitute departures from the spirit and scope. of the invention.

The embodiments of the invention in which an exclusive property' orprivilege is claimed are defined as follows:

l. Valving mechanism for use in a double-acting hydraulic oil well pumphaving a central sliding piston rod with upper and lower pistons thereonlocated in a pump barrel, said valving mechanism comprising:

inner mandrel means snugly encircling the piston rod of the pump inslidable relationship therewith; port means passing through said innermandrel means;

passing means between said inner mandrel means and the piston rod andadapted for communication with said port means;

housing means concentrically mounted about said inner manadrel means andadapted to allow sliding movement of said inner mandrel means therein;said housing means further adapted to be interconnected between and inaxial alignment with two sections of pump barrel;

flow passage means through said housing means arranged to be placed incommunication with said inner mandrel port means;

seal means between said housing means and the oil well tubing innerdiameter; and,

hydraulic damping means between said inner mandrel means and saidhousing means arranged to provide fluidic resistance to rapid movementof said inner mandrel means with respect to said housing means.

2. The valving mechanism of claim 1 further comprising travel limitmeans between said inner mandrel means and said housing means arrangedto limit upward and downward movement of said inner mandrel means insaid housing means.

3. The valving mechanism of claim 1 wherein said damping means furthercomprises ring means securedly mounted on said inner mandrel means andextending into an inner annular chamber area in said housing means withrestricted annular flow passages above and below said chamber areaarranged to allow restricted fluid flow into and out of said chamberarea in response to axial movement of said ring means through saidchamber.

4. A reversing valve assembly for use in hydraulically actuated oil wellpumps of the type having two pistons slidably mounted vertically in apump barrel and connected by a central piston rod; said valve assemblycomprising:

a cylindrical tubular inner mandrel slidably located about the centralpiston rod;

upper port means passing through the wall of said inner mandrel; upperpassage means in the upper end of said inner mandrel communicating saidupper port means with a chamber below the upper pump piston;

lower port means passing through the wall of said inner mandrel;

lower passage means communicating said lower port means with a chamberabove the lower piston in the pump; generally cylindrical tubularhousing means mounted externally on said inner mandrel and adapted toallow sliding movement of said mandrel therein;

6 upper exit port means passing through the wall of the upper portion ofsaid housing means and arranged to be placed in communication with saidmandrel upper port means;

upper entrance port means passing through the wall of the upper portionof said housing means below said upper exit port means and arranged tobe placed in commuication with said mandrel upper port means;

upper packing means located in sealing abutment between said housingmeans and the inner wall of the well tubing, said upper packing meansbeing located on said housing means between said upper exit port meansand said upper entrance port means;

lower entrance port means passing through the wall of the lower portionof said housing means and arranged to be placed in communication withsaid mandrel lower port means;

lower exit port means passing through the wall of the lower portion ofsaid housing means below said lower entrance port means and arranged tobe placed in communication with said mandrel lower port means; and

lower packing means sealingly mounted between said housing means and theinner wall of the well tubing and located between said lower entranceport means and said lower exit port means;

said inner mandrel arranged between the pump pistons to be actuatedupward and downward by abutment with the pistons between a firstconfiguration and a second configuration in said housing means, whereinsaid first configuration places said upper entrance port means incommunication with said mandrel upper port means and said lower exitport means in communication with said mandrel lower port means, and saidsecond configuration places said upper exit port means in communicationwith said mandrel upper port means and said lower entrance port means incommunication with said mandrel lower port means.

5. The reversing valve assembly of claim 4 further comprising hydraulicdamping means between said inner mandrel and said housing means, saiddamping means comprising ring means mounted annularly on said innermandrel and projecting into an hydraulic damping chamber formed in saidhousing means, said ring means adapted to move vertically in saidchamber and substantially prevent flow of fluids between said ring meansand said chamber wall, with restricted flow passages at the top andbottom of said chamber arranged to allow only a restricted flow of fluidfrom said chamber -and thereby retard movement of said ring meanstherein.

1. Valving mechanism for use in a double-acting hydraulic oil well pumphaving a central sliding piston rod with upper and lower pistons thereonlocated in a pump barrel, said valving mechanism comprising: innermandrel means snugly encircling the piston rod of the pump in slidablerelationship therewith; port means passing through said inner mandrelmeans; passing means between said inner mandrel means and the piston rodand adapted for communication with said port means; housing meansconcentrically mounted about said inner manadrel means and adapted toallow sliding movement of said inner mandrel means therein; said housingmeans further adapted to be interconnected between and in axialalignment with two sections of pump barrel; flow passage means throughsaid housing means arranged to be placed in communication with saidinner mandrel port means; seal means between said housing means and theoil well tubing inner diameter; and, hydraulic damping means betweensaid inner mandrel means and said housing means arranged to providefluidic resistance to rapid movement of said inner mandrel means withrespect to said housing means.
 2. The valving mechanism of claim 1further comprising travel limit means between said inner mandrel meansand said housing means arranged to limit upward and downward movement ofsaid inner mandrel means in said housing means.
 3. The valving mechanismof claim 1 wherein said damping means further comprises ring meanssecuredly mounted on said inner mandrel means and extending into aninner annular chamber area in said housing means with restricted annularflow passages above and below said chamber area arranged to allowrestricted fluid flow into and out of said chamber area in response toaxial movement of said ring means through said chamber.
 4. A reversingvalve assembly for use in hydraulically actuated oil well pumps of thetype having two pistons slidably mounted vertically in a puMp barrel andconnected by a central piston rod; said valve assembly comprising: acylindrical tubular inner mandrel slidably located about the centralpiston rod; upper port means passing through the wall of said innermandrel; upper passage means in the upper end of said inner mandrelcommunicating said upper port means with a chamber below the upper pumppiston; lower port means passing through the wall of said inner mandrel;lower passage means communicating said lower port means with a chamberabove the lower piston in the pump; generally cylindrical tubularhousing means mounted externally on said inner mandrel and adapted toallow sliding movement of said mandrel therein; upper exit port meanspassing through the wall of the upper portion of said housing means andarranged to be placed in communication with said mandrel upper portmeans; upper entrance port means passing through the wall of the upperportion of said housing means below said upper exit port means andarranged to be placed in commuication with said mandrel upper portmeans; upper packing means located in sealing abutment between saidhousing means and the inner wall of the well tubing, said upper packingmeans being located on said housing means between said upper exit portmeans and said upper entrance port means; lower entrance port meanspassing through the wall of the lower portion of said housing means andarranged to be placed in communication with said mandrel lower portmeans; lower exit port means passing through the wall of the lowerportion of said housing means below said lower entrance port means andarranged to be placed in communication with said mandrel lower portmeans; and lower packing means sealingly mounted between said housingmeans and the inner wall of the well tubing and located between saidlower entrance port means and said lower exit port means; said innermandrel arranged between the pump pistons to be actuated upward anddownward by abutment with the pistons between a first configuration anda second configuration in said housing means, wherein said firstconfiguration places said upper entrance port means in communicationwith said mandrel upper port means and said lower exit port means incommunication with said mandrel lower port means, and said secondconfiguration places said upper exit port means in communication withsaid mandrel upper port means and said lower entrance port means incommunication with said mandrel lower port means.
 5. The reversing valveassembly of claim 4 further comprising hydraulic damping means betweensaid inner mandrel and said housing means, said damping means comprisingring means mounted annularly on said inner mandrel and projecting intoan hydraulic damping chamber formed in said housing means, said ringmeans adapted to move vertically in said chamber and substantiallyprevent flow of fluids between said ring means and said chamber wall,with restricted flow passages at the top and bottom of said chamberarranged to allow only a restricted flow of fluid from said chamber andthereby retard movement of said ring means therein.